The formation of phosphorous surface inverse segregation （SIS） in twin-roll cast strips of low-carbon steels was studied. High phosphorous strips were fabricated by using a pilot twin-roll strip caster and a melt/su...The formation of phosphorous surface inverse segregation （SIS） in twin-roll cast strips of low-carbon steels was studied. High phosphorous strips were fabricated by using a pilot twin-roll strip caster and a melt/substrate contacting apparatus, respectively. Solidification structures of strips were observed and analyzed, and phosphorus distributions along longitudinal sections of strips were investigated and discussed. The results showed that solidification structures of all strips were columnar grains, either integrated or coarse in the strip made by the melt/substrate contacting apparatus or damaged in some degree in cast strips; and that during cast strip solidification, enrichment of phosphorus occurred between columnar grains, and the average phosphorus concentration near the surface in the strip with 0.15% of phosphorus was measured to be about 0.27% which was obviously higher than that in the bulk.展开更多
The present work is focused on the influence of annealing atmosphere on the microstructure and mechanical property of free-cutting phosphor bronze alloy.The annealing of the alloy was conducted in the three kinds of a...The present work is focused on the influence of annealing atmosphere on the microstructure and mechanical property of free-cutting phosphor bronze alloy.The annealing of the alloy was conducted in the three kinds of annealing atmosphere such as air,vacuum and nitrogen.After annealing,a discernable difference in recystallized grain size and lead particle size was not appeared with different annealing atmosphere.The tensile strength of the alloy annealed in air or nitrogen atmosphere was higher than that of those annealed in vacuum atmosphere.In thecase of the alloy annealed in vacuum atmosphere,the mechanical strength was reduced by vaporization of zinc.In the case of annealing in nitrogen and in air atmosphere,the sweating of lead was occurred.However,the inverse segregation of lead was suppressed by copper oxide layer on the surface annealed in air.This copper oxide layer leads to a decrease of the yield during fabrication process. Therefore,annealing of the alloy in nitrogen atmosphere is favorable in terms of the mechanical strength and yield.展开更多
The Cu-15Ni-8Sn alloy has been widely used in aerospace,marine engineering and electronic components due to its exceptional mechanical properties,corrosion resistance and high-temperature softening resistance.The inve...The Cu-15Ni-8Sn alloy has been widely used in aerospace,marine engineering and electronic components due to its exceptional mechanical properties,corrosion resistance and high-temperature softening resistance.The inverse segregation and coarse microstructure that easily form during traditional casting processes significantly reduce the processing and mechanical properties of the Cu-15Ni-8Sn alloy after subsequent plastic deformation.The brittle discontinuous precipitates(DP)that emerge during the later stages of ageing can also significantly decrease the ductility of the Cu-15Ni-8Sn alloy.Therefore,introducing advanced techniques to refine the as-cast microstructure,suppress inverse segregation and suppress DP has become essential for preparing a high-performance Cu-15Ni-8Sn alloy.Multimode magnetic fields and microalloying methods are considered among the most effective techniques for regulating the microstructure.This work critically reviews the effects of multimode magnetic fields and microalloying techniques on refining the as-cast microstructure,mitigating inverse segregation and suppressing DP in the Cu-15Ni-8Sn alloy,aiming to provide new insights for its high-performance preparation.展开更多
基金Item Sponsored by National Basic Research Program of China (2004CB619108)National Natural Science Foundation ofChina (50574018)
文摘The formation of phosphorous surface inverse segregation （SIS） in twin-roll cast strips of low-carbon steels was studied. High phosphorous strips were fabricated by using a pilot twin-roll strip caster and a melt/substrate contacting apparatus, respectively. Solidification structures of strips were observed and analyzed, and phosphorus distributions along longitudinal sections of strips were investigated and discussed. The results showed that solidification structures of all strips were columnar grains, either integrated or coarse in the strip made by the melt/substrate contacting apparatus or damaged in some degree in cast strips; and that during cast strip solidification, enrichment of phosphorus occurred between columnar grains, and the average phosphorus concentration near the surface in the strip with 0.15% of phosphorus was measured to be about 0.27% which was obviously higher than that in the bulk.
文摘The present work is focused on the influence of annealing atmosphere on the microstructure and mechanical property of free-cutting phosphor bronze alloy.The annealing of the alloy was conducted in the three kinds of annealing atmosphere such as air,vacuum and nitrogen.After annealing,a discernable difference in recystallized grain size and lead particle size was not appeared with different annealing atmosphere.The tensile strength of the alloy annealed in air or nitrogen atmosphere was higher than that of those annealed in vacuum atmosphere.In thecase of the alloy annealed in vacuum atmosphere,the mechanical strength was reduced by vaporization of zinc.In the case of annealing in nitrogen and in air atmosphere,the sweating of lead was occurred.However,the inverse segregation of lead was suppressed by copper oxide layer on the surface annealed in air.This copper oxide layer leads to a decrease of the yield during fabrication process. Therefore,annealing of the alloy in nitrogen atmosphere is favorable in terms of the mechanical strength and yield.
基金supported by the National Natural Science Foundation of China(Grants 52204392,52474411,52274385 and 52204347)the Young Elite Scientists Sponsorship Programme by CAST(Grant 2022QNRC001)the National Key Research and Development Program of China(Grant 2022YFC2904900).
文摘The Cu-15Ni-8Sn alloy has been widely used in aerospace,marine engineering and electronic components due to its exceptional mechanical properties,corrosion resistance and high-temperature softening resistance.The inverse segregation and coarse microstructure that easily form during traditional casting processes significantly reduce the processing and mechanical properties of the Cu-15Ni-8Sn alloy after subsequent plastic deformation.The brittle discontinuous precipitates(DP)that emerge during the later stages of ageing can also significantly decrease the ductility of the Cu-15Ni-8Sn alloy.Therefore,introducing advanced techniques to refine the as-cast microstructure,suppress inverse segregation and suppress DP has become essential for preparing a high-performance Cu-15Ni-8Sn alloy.Multimode magnetic fields and microalloying methods are considered among the most effective techniques for regulating the microstructure.This work critically reviews the effects of multimode magnetic fields and microalloying techniques on refining the as-cast microstructure,mitigating inverse segregation and suppressing DP in the Cu-15Ni-8Sn alloy,aiming to provide new insights for its high-performance preparation.
